花魔芋和白魔芋褐变机理及褐变抑制研究

Browning mechanism and inhibition of Amorphophallus Konjac and Amorphophallus albus

该文通过研究花魔芋和白魔芋球茎中酚类物质含量、多酚氧化酶(PolyphenolOxidase,PPO)活性、褐变底物和干燥脱水过程中褐变的机理,探讨了无公害酶促褐变抑制剂植酸、抗坏血酸、柠檬酸、L-半胱氨酸对魔芋褐变的抑制效果。结果表明:从11月至次年1月,白魔芋球茎的总酚含量始终高于花魔芋,花魔芋的PPO活力始终强于白魔芋,白魔芋的褐变强度始终弱于花魔芋的褐变强度,褐变强度跟魔芋球茎PPO活力呈正相关。引起魔芋褐变的主要底物可能是多巴胺。引起白魔芋和花魔芋褐变的酶均为多酚氧化酶。对白魔芋采用0.01%L-半胱氨酸单因子抑制剂浸泡5min,并在60℃下烘烤,所得白魔芋干片颜色白,效果最好。对花魔芋采用0.15%L-半胱氨酸+1%柠檬酸+1%植酸+0.01%抗坏血酸组合抑制剂浸泡5min,并在60℃下烘烤,所得魔芋干片颜色白,效果最好。

The phenol contents, Polyphenol Oxidase （PPO） activity, browning substrates and the browning mechanism during process of desiccation of Amorphophallus Konjac （AK） and Amorphophallus albus （AA） were studied. And the inhibition effects of nuisance-free enzymatic browning inhibitors, such as phytic acid, ascorbic acid, citric acid and cysteine were investigated. Results show that during the storage from November to January of next year, the total phenol content in the corm of AA is higher than that in the AK, the PPO activity of AK is higher than that of AA, the browning intensity of AA is always weaker than that of AK, and the browning intensity has positive correlation with the PPO activity of konjac corm. The substrate which causes browning is dopamine mostly. The enzyme which arouse the browning of AK and AA is polyphenol oxidase. The AA dry slice is white in color and has good quality which can be obtained by the process of dipping it in the solution containing 0.01 % cysteine for about 5 min and firing at 60℃. The AK dry slice is white in color and good in quality which can be obtained by the process of dipping it in the solution containing 0. 15% cysteine ＋ 1% citric acid ＋ 1% phytic acid ＋ 0.01 % ascorbic acid for around 5 min and then firing at 60℃.